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inmem.go
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inmem.go
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// Copyright 2016 The OPA Authors. All rights reserved.
// Use of this source code is governed by an Apache2
// license that can be found in the LICENSE file.
// Package inmem implements an in-memory version of the policy engine's storage
// layer.
//
// The in-memory store is used as the default storage layer implementation. The
// in-memory store supports multi-reader/single-writer concurrency with
// rollback.
//
// Callers should assume the in-memory store does not make copies of written
// data. Once data is written to the in-memory store, it should not be modified
// (outside of calling Store.Write). Furthermore, data read from the in-memory
// store should be treated as read-only.
package inmem
import (
"context"
"fmt"
"io"
"sync"
"sync/atomic"
"github.com/open-policy-agent/opa/ast"
"github.com/open-policy-agent/opa/storage"
"github.com/open-policy-agent/opa/util"
)
// New returns an empty in-memory store.
func New() storage.Store {
return &store{
data: map[string]interface{}{},
triggers: map[*handle]storage.TriggerConfig{},
policies: map[string][]byte{},
indices: newIndices(),
}
}
// NewFromObject returns a new in-memory store from the supplied data object.
func NewFromObject(data map[string]interface{}) storage.Store {
db := New()
ctx := context.Background()
txn, err := db.NewTransaction(ctx, storage.WriteParams)
if err != nil {
panic(err)
}
if err := db.Write(ctx, txn, storage.AddOp, storage.Path{}, data); err != nil {
panic(err)
}
if err := db.Commit(ctx, txn); err != nil {
panic(err)
}
return db
}
// NewFromReader returns a new in-memory store from a reader that produces a
// JSON serialized object. This function is for test purposes.
func NewFromReader(r io.Reader) storage.Store {
d := util.NewJSONDecoder(r)
var data map[string]interface{}
if err := d.Decode(&data); err != nil {
panic(err)
}
return NewFromObject(data)
}
type store struct {
rmu sync.RWMutex // reader-writer lock
wmu sync.Mutex // writer lock
xid uint64 // last generated transaction id
data map[string]interface{} // raw data
policies map[string][]byte // raw policies
triggers map[*handle]storage.TriggerConfig // registered triggers
indices *indices // data ref indices
}
type handle struct {
db *store
}
func (db *store) NewTransaction(ctx context.Context, params ...storage.TransactionParams) (storage.Transaction, error) {
var write bool
var context *storage.Context
if len(params) > 0 {
write = params[0].Write
context = params[0].Context
}
xid := atomic.AddUint64(&db.xid, uint64(1))
if write {
db.wmu.Lock()
} else {
db.rmu.RLock()
}
return newTransaction(xid, write, context, db), nil
}
func (db *store) Commit(ctx context.Context, txn storage.Transaction) error {
underlying := txn.(*transaction)
if underlying.write {
db.rmu.Lock()
event := underlying.Commit()
db.indices = newIndices()
db.runOnCommitTriggers(ctx, txn, event)
db.rmu.Unlock()
db.wmu.Unlock()
} else {
db.rmu.RUnlock()
}
return nil
}
func (db *store) Abort(ctx context.Context, txn storage.Transaction) {
underlying := txn.(*transaction)
if underlying.write {
db.wmu.Unlock()
} else {
db.rmu.RUnlock()
}
}
func (db *store) ListPolicies(_ context.Context, txn storage.Transaction) ([]string, error) {
underlying := txn.(*transaction)
return underlying.ListPolicies(), nil
}
func (db *store) GetPolicy(_ context.Context, txn storage.Transaction, id string) ([]byte, error) {
underlying := txn.(*transaction)
return underlying.GetPolicy(id)
}
func (db *store) UpsertPolicy(_ context.Context, txn storage.Transaction, id string, bs []byte) error {
underlying := txn.(*transaction)
return underlying.UpsertPolicy(id, bs)
}
func (db *store) DeletePolicy(_ context.Context, txn storage.Transaction, id string) error {
underlying := txn.(*transaction)
if _, err := underlying.GetPolicy(id); err != nil {
return err
}
return underlying.DeletePolicy(id)
}
func (db *store) Register(ctx context.Context, txn storage.Transaction, config storage.TriggerConfig) (storage.TriggerHandle, error) {
underlying := txn.(*transaction)
if !underlying.write {
return nil, &storage.Error{
Code: storage.InvalidTransactionErr,
Message: "triggers must be registered with a write transaction",
}
}
h := &handle{db}
db.triggers[h] = config
return h, nil
}
func (db *store) Read(ctx context.Context, txn storage.Transaction, path storage.Path) (interface{}, error) {
underlying := txn.(*transaction)
return underlying.Read(path)
}
func (db *store) Write(ctx context.Context, txn storage.Transaction, op storage.PatchOp, path storage.Path, value interface{}) error {
underlying := txn.(*transaction)
val := util.Reference(value)
if err := util.RoundTrip(val); err != nil {
return err
}
return underlying.Write(op, path, *val)
}
func (db *store) Build(ctx context.Context, txn storage.Transaction, ref ast.Ref) (storage.Index, error) {
underlying := txn.(*transaction)
if underlying.write {
return nil, &storage.Error{
Code: storage.IndexingNotSupportedErr,
Message: "in-memory store does not support indexing on write transactions",
}
}
return db.indices.Build(ctx, db, txn, ref)
}
func (h *handle) Unregister(ctx context.Context, txn storage.Transaction) {
underlying := txn.(*transaction)
if !underlying.write {
return
}
delete(h.db.triggers, h)
}
func (db *store) runOnCommitTriggers(ctx context.Context, txn storage.Transaction, event storage.TriggerEvent) {
for _, t := range db.triggers {
t.OnCommit(ctx, txn, event)
}
}
var doesNotExistMsg = "document does not exist"
var rootMustBeObjectMsg = "root must be object"
var rootCannotBeRemovedMsg = "root cannot be removed"
var outOfRangeMsg = "array index out of range"
var arrayIndexTypeMsg = "array index must be integer"
func invalidPatchError(f string, a ...interface{}) *storage.Error {
return &storage.Error{
Code: storage.InvalidPatchErr,
Message: fmt.Sprintf(f, a...),
}
}
func notFoundError(path storage.Path) *storage.Error {
return notFoundErrorHint(path, doesNotExistMsg)
}
func notFoundErrorHint(path storage.Path, hint string) *storage.Error {
return notFoundErrorf("%v: %v", path.String(), hint)
}
func notFoundErrorf(f string, a ...interface{}) *storage.Error {
msg := fmt.Sprintf(f, a...)
return &storage.Error{
Code: storage.NotFoundErr,
Message: msg,
}
}